Found this while walking the dogs. Think it might be an English half crown. The old silver coins are really hard to clean from round here. The newer ones come up a treat after 24 hours in lemon juice. Has anyone got any tricks to clean up sterling silver coins with that hard black crust?

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Wow ! Great pick up , certainly looks to be a half crown . The half and full crown have been on my want list for a long time , many thousands of coins later still no luck , and you just pick one up , amazing . To remove the black from full silvers try spitting on the coin then wrapping tightly in alfoil . You will feel heat generated and smell hydrogen sulphide , when reaction stops rub the coin under running water , then if it looks clean enough polish with a bi carb rub , if not repeat the process . Post 1945 silvers don't respond very well to this treatment due to their lower silver content .

Cheers junkhunter. She's in pretty rough condition, not much detail left in the areas that had the black crust on. Still pretty stoked and made all the scrap metal and 1 and 2c coins worth it. Lookin for the full one now!

Nice work Dave , those medallions turn up a bit but still a very cool find . They were also made in vastly fewer numbers of silver , i think i read somewhere that the silver ones were given to officers children . Still looking for the silver model !

Yeah, most of the Commonwealth and roo pennies I've found have been in much worse condition. Think the British ones were bronze rather than copper. Hopefully theres a few more out there cos I love the look of them and also thinking about who might have lost them and what they were doing at the time.